1. Field of the Invention
The present invention relates to a novel integrated process for the environmentally benign use of grains and renewable materials to produce xe2x80x9cclean beefxe2x80x9d (or milk), fuel ethanol for motor fuel purposes, and bio-gas/bio-fertilizer from animal wastes.
2. Background of the Prior Art
American agriculture in general, and the livestock feeding industry in particular, face increasing pressures which pose challenges to traditional methods of doing business, and offer opportunities to those with improved methods. Trends in the marketplace have created a demand for xe2x80x9cclean beefxe2x80x9d (beef which is hormone-, antibiotics-, and E.coli- free). Environmental authorities at both the national and local levels are imposing requirements on large animal feeding operations to ensure that odor and environmental contamination are substantially reduced from current levels. Cost effective methods of converting animal wastes into marketable fuels and products are needed. These methods and products should be generally xe2x80x9csustainablexe2x80x9d (e.g., renewable) and environmentally friendly.
In conventional practice, cattle are normally fed 22 pounds of dry matter equivalent per day with as much as a 50% moisture content for a total feed weight of approximately 44 pounds per day. The moisture content represents a portion of the animal""s total daily water intake. Cattle on average convert 6.5 pounds of feed into one pound of body weight gain. If the animal gains 3.5 pounds of weight per day and requires 6.5 pounds of feed per pound of gain, it must consume 22.75 pounds of dry matter feed per day. This diet not only allows for weight gain but provides the energy to sustain the animal in good health. Approximately 70% of the animal""s dry matter feed ration is digestible. The non-digestible and water portions are passed as manure and urine which in conventional practice are typically dumped onto the ground. The pens are then occasionally cleaned by scraping the manure and dirt mixture into wind row piles where it sun-dries. The mixture is eventually field applied, sold as fertilizer or disposed of in some fashion. Due to growing environmental concerns, however, manure management is rapidly becoming one of the most critical functions in commercial feeding operations.
Modern feedyards are designed to catch the water runoff from cattle pens in special drain basins or pits which are often aerated to introduce more oxygen into them. The water will evaporate as new runoff continuously refills the pits. They are designed to normally handle up to a 25-year rain runoff However, in just the last 25 years, there have been not only 25-year rains but a 50, 100 and even a 300-year rain in the Midwest. These heavy rains can, and do, overwhelm the feedyards"" ability to manage the pen drainage systems.
Since the early 1990""s, many states and the federal government have begun to review the public policies regulating commercial cattle feeding. Many complaints have been received from environmentalists, naturalists, fishermen and neighbors regarding the untreated contamination resulting from the feedyards. The sheer volume of cattle waste (12 times that of one adult human per day) is cause for considerable concern. Whereas human waste is treated in sewage disposal plants, septic tanks or by other approved methods, conventionally, cattle waste is not so treated.
The United States has a population of approximately 275 million people and raises approximately 100 million cattle, of which over 32 million are brought together in confined commercial feedlots. If each adult animal produces 12 times as much waste as an adult human being, the United States is producing the animal waste-equivalent of a nation of 385 million people, just in feedyards.
It is these feedyard cattle that are posing the greatest threat to the environment. Cattle on farms and ranches average approximately one animal for each 12 acres or about one animal per 500,000 square feet, whereas, in a confined feedyard operation, one animal has an average of 250 square feet. This animal density concentrates the manure into very small areas and local ecosystems are thereby jeopardized.
Commercial cattle feeding (feedyards larger than 1,000 animal units) are the point source for numerous real and perceived environmental problems: water contamination, airborne particulates, objectionable odors, fly and insect infestations, nitrogen and phosphorus buildup in the soil and major fish kills in rivers and streams. The troublesome greenhouse gas (GHG) emissions of methane is another major environmental problem. Worldwide, cattle are the single largest animal source of methane release into the environment (methane is 22 times more potent than CO2 as a greenhouse gas).
Most states require freshly applied raw animal manure to be incorporated into the soil at a depth of at least nine inches, and within 12 hours of manure application. This is the most economic use of feedyard manure today. Feedyards that recover manure but do not keep it separated and free from dirt contamination, will normally sell the pen scrapings in a dry form. However, this method is more labor intensive and requires additional equipment and real estate for wind row drying. At this point, the waste byproduct can pollute the surrounding environment if washed away during wet periods and the opportunity for odor and insect problems increases.
Another major environmental concern caused by commercial cattle feeding is the build-up of nitrogen and phosphorus in the soil under and around feedyards where manure is applied or disposed of. This build-up comes from the long-term consumption, and then concentration, of feed grain in the relatively small area encompassed by a feedlot. A typical feedyard will consume approximately 20 pounds of corn per animal per day. In a 25,000 head feedyard that is full with year-round operation, this amounts to approximately 3,250,000 bushels of corn per year.
In the corn belt of the upper Midwest each acre of corn receives approximately 135 pounds of nitrogen per acre and will yield approximately 130 bushels of corn per acre. When the mature corn is harvested only the seed is saved and the plant is reincorporated into the soil for nutritional enrichment. The 130 bushels of seed corn taken from the acre contain most of the nitrogen and phosphorus which is then transported to the cattle feedyard for feed rations. If a typical 25,000 head location utilizes 3.25 million bushels per year and the average production is 130 bushels per acre, the feedyard will require all of the output from 25,000 acres of corn.
If a conventional 25,000 head feedyard is built on approximately 250 acres of land, this means the nitrogen and phosphorus is taken from 25,000 acres of corn and ends up on 250 acres of feedlotxe2x80x94a concentration of 100-fold. During the feeding cycle, cattle use approximately one-half of the nitrogen in the corn for body growth by converting it to protein. Thus, this portion of the nitrogen leaves the feedyard as meat. The remaining 50% of nitrogen and 100% of the phosphorus is left behind. The manure management of the feedyard must then move these compounds back to local farm fields as replacement fertilizer needed for next year""s corn crop.
If the feedyard does not collect and remove these compounds from the land it will end up in the environment. The nitrogen and phosphorous can remain in the land under the feedyard and be trapped there until the end of the feedyard""s life cycle. Or, they can be transported off site via water runoff, airborne particulates, manure removal or disposal, etc. The principal environmental concern is that heavy buildup of nitrogen and phosphorus can enter the water system, as in the widely reported instances of runoff from Midwestern states like Iowa and Illinois into the Mississippi River, and ultimate deposit in heavy concentrations in the Gulf of Mexico and elsewhere, causing immense xe2x80x9cdead zonesxe2x80x9d which cause the death of shrimp and other fish due to oxygen depletion.
While anaerobic digestion of manure has been known for some time, it has never been practiced on a large scale basis in cattle feedlots due to poor economics, inability to prevent manure contamination by soil and water and limited outlets for the bio-methane.
It is clear that a new approach to cattle feeding is needed in order to address the concerns of environmental regulators, consumers, and the economic pressures facing the industry itself.
Recent outbreaks of E. Coli-contaminated meat, and growing consumer demand for xe2x80x9ccleanxe2x80x9d beef have combined to put significant pressure on livestock producers, feedlot operators, and meat packers. In the U.S. conventional feeding methods rely upon heavy use of anabolic steroids, antibiotics, and other artificial practices to promote animal weight gain. However, the U.S. Food and Drug Administration (FDA) has expressed growing concern over the threat posed by excessive antibiotics use in animal feeding, which experts now link to the proliferation of drug-resistant bacteria, and increasing humans"" vulnerability to untreatable infections.
Moreover, food safety officials have expressed growing concern about the long-term health effects of eating beef which contains high levels of antibiotics and growth hormones, and many nations prohibit the importation of U.S. beef that contains growth-enhancing steroids, hormones, and other xe2x80x9cartificialxe2x80x9d additives. Consequently, consumer demand for beef has declined.
A recent Presidential Executive Order set a national goal of tripling the production and use of biofuels by the year 2010, in large part due to the need to achieve substantial reductions in emissions of greenhouse gases such as carbon dioxide (CO2) and methane. Primary sources of CO2 are fossil fuel combustion, and a primary source of methane emissions is cattle flatulence and manure. Renewable biofuels such as ethanol and bio-gas using conventional methods are not cost competitive with fossil fuels, and new approaches are needed if the production goals are to be met. One of the most capital- and energy-intensive sections of modern-day ethanol plants is the spent mash (protein co-product) drying and handling section. The protein co-product is valued as an effective feed ingredient for ruminant animals (cattle and dairy cows), but in traditional practice must be dried before it can be transported and stored. Eliminating this requirement would result in substantial capital, energy and operating cost savings in ethanol production.
Accordingly, one objective of the present invention is to provide an integrated system which makes anaerobic digestion of livestock manure an economically viable operation.
Another object of the present invention is to provide a subsystem for a livestock feedlot which is integrated with ethanol production in such a manner that the economics of both the ethanol production and the feedlot operation are enhanced.
Still another object of the present invention is integration of anaerobic digestion of livestock waste with ethanol production in such a manner that the economics of both the ethanol production and the anaerobic digestion are enhanced.
Yet another object of the present invention is to provide a livestock feedlot operation which utilizes a feed that is efficient in terms of weight gain, that enables the elimination of anabolic steroids and antibiotics, and that reduces livestock flatulence.
Another objective of the present invention is to provide cattle feeding enclosures with concrete slatted floors and manure collection systems so as to prevent contamination of the manure by dirt, water, or other foreign materials that would interfere with the organisms used in the anaerobic digestion system.
Another objective of the present invention is to utilize xe2x80x9cHigh Saturationxe2x80x9d wet distillers"" grains with solubles (xe2x80x9cWDGSxe2x80x9d) feed rations for beef and/or dairy cattle such that conversion efficiencies and the animals"" health are significantly improved, and meat/milk quality is significantly improved.
Another object of the present invention is to reduce/eliminate the incidence of E. coli in beef cattle by utilizing xe2x80x9chigh saturationxe2x80x9d WDGS rations to eliminate acidosis, typically caused by excessive starch in the feeding ration.
Another object of the present invention is to ensure the reliable supply of WDGS, in required quality and quantities, to ruminant animals by locating the ethanol unit adjacent to their confinement location, thus eliminating long distance transport and the need for expensive drying.
Another object of the present invention is to reduce/eliminate the use of anabolic steroids and growth hormones, made possible by the increased conversion efficiencies achieved with xe2x80x9chigh saturationxe2x80x9d WDGS rations with their xe2x80x9chigh bypassxe2x80x9d (into the second stomach) characteristics.
Another objective of the present invention is to reduce/eliminate the use of antibiotics in cattle feedlots, by creating a much more sanitary environment through use of concrete slatted floors, immediate manure collection, and anaerobic digestion system.
Another objective of the present invention is to utilize the xe2x80x9cnaturalxe2x80x9d concentrated protein in WDGS to improve the starch: protein balance of the traditional cattle ration, and enable the replacement of external protein sources such as urea and alfalfa hay, thus reducing feeding costs, and simplifying a cattle operation""s sourcing and inventory requirements.
Another objective of the present invention is to reduce/eliminate cattle feedlot odor and water contamination by rapid transfer of the cattle waste into the anaerobic digestion system, and destruction of the pathogens by the conversion of the cattle waste into bio-gas, bio-fertilizer, and bio-sludge.
Another object of the present invention is to make the production of biofuels like ethanol and bio-gas cost competitive with fossil fuels, by exploiting synergies to reduce capital and operating costs, and maximizing returns on all of the co-products.
Another object of the present invention is to eliminate the need for the capital intensive, and costly to operate and maintain, spent grain mash drying equipment in the ethanol plant.
Another object of the present invention is to substantially reduce the emissions of greenhouse gases such as CO2 and methane to the atmosphere, thus reducing the threat of global warming.
Another object of the present invention is to eliminate the economic costs, and fossil fuel consumption and emissions, that arise from the conventional practice of transportation between disaggregrated production sites (e.g., corn fields, corn drying facilities, ethanol plants, and cattle feedlots).
Another objective of the present invention is to reduce the use of fossil fuel fertilizers, and break the nitrogen/phosphate build-up cycle that is causing massive xe2x80x9cdead zonesxe2x80x9d in the Gulf of Mexico and other waterways due to field runoff.
The present invention positively addresses the foregoing objectives, and departs from conventional practice by continuous integration of three sub-systems:
1) a feedyard which encloses livestock over slatted floors for manure disposal and contamination prevention, disease control, and climate protection;
2) an anaerobic digestion/bio-fertilizer recovery system, which collects manure from below the slatted floors and converts it into bio-methane and bio-fertilizer; and
3) an ethanol plant, without traditional spent grain mash drying equipment, and which is powered by the bio-gas recovery energy system.
Taken together, the three xe2x80x9csub-systemsxe2x80x9d of the present invention, which have never before been integrated in a continuous operation, create the conditions for cost-effective production of xe2x80x9cclean beefxe2x80x9d, ethanol, and bio-gas, and simultaneous reductions in environmental pollution linked to livestock feeding operations. Each of the three xe2x80x9csubsystemsxe2x80x9d is dependent upon the other, from the perspective of both operational and economic efficiencies. For example, the ethanol plant would require expensive mash drying equipment if there were no feedlot; the anaerobic digestion system would not be economically viable if the ethanol plant could not utilize its bio-methane; and the slatted floor feedlot design is critical to prevent manure contamination from interfering with the efficient operation of the anaerobic digestion system.
The present invention differs from conventional practice in several important ways:
1) Ethanol production and livestock feeding are done at the same site, and the animals fed in covered, slatted concrete floor lots. The concrete floors prevent manure contamination by dirt, water, and other foreign materials, and are essential for the cost effective conversion of cattle waste into bio-gas by the anaerobic digestion unit. This manner of animal husbandry also prevents prolonged animal exposure to disease-bearing wastes, and costly weight losses associated with mud and cold exposure, even in northern climes.
Integration of an ethanol unit with the feedlot justifies the investment in an anaerobic digestion unit, since the ethanol plant (unlike the feedlot standing alone) can utilize the bio-gas produced from the livestock waste. At current electricity and natural gas prices, the fossil fuel energy savingsxe2x80x94from the combination of elimination of mash drying and the use of the bio-gas xe2x80x94amounts to millions of dollars annually.
2) The sizes of the ethanol unit and the feedlot can be balanced so that all of the high protein WDGS can be fed xe2x80x9cwetxe2x80x9d directly to the cattle, without capital- and energy-intensive drying, and freight. Compared to a conventional ethanol plant of the same capacity, the present invention""s simplified ethanol plant""s capital costs will be reduced by up to 30%. In effect, the present invention""s ethanol unit serves dual purposes as the feed pretreatment center for xe2x80x9cclean beefxe2x80x9d and as a plant for producing ethanol as a xe2x80x9cco-productxe2x80x9d.
3) A feeding ration of 25% or more WDGS (xe2x80x9chigh saturationxe2x80x9d WDGS) feeding reduces/eliminates acidosis and liver failure, which have been linked to the formation of E. Coli 0157:H7 (xe2x80x9cE. Colixe2x80x9d) in ruminant animals such as beef cattle.
4) Operations and maintenance requirements are greatly simplified, and overall labor costs are reduced. The most important simplifying factor is the elimination of equipment and process duplication in grain handling, energy systems, infrastructure, transportation, etc. However, other operating benefits come from the enclosure of the cattle, the easy proximity of the WDGS for ration formulation, and the improved management of the manure.
5) CO2 may be captured from the ethanol unit, and used for meat processing or other applications. All process water is recycled for use in the digester, ethanol plant, or for irrigation of nearby fields, other parts of the operation. In short, waste is virtually eliminated, and emissions of both CO2 and methane are substantially reduced.